The invention relates generally to precast insulated concrete wall panels and, more specifically, to a precast insulated concrete wall panel having an air gap between the exterior concrete layer and the insulation layer to assist in the response of the wall to certain conditions and to a novel connector for use in fabricating the wall panels.
Precast insulated concrete wall panels are well known in the art and offer a number of advantages for residential and commercial building construction. These advantages include shorter construction schedules, improved thermal resistance, improved quality control, and enhanced durability. However, conventional concrete wall panels are heavy, thus increasing the cost of transporting the panels from the precasting plant to the job site. The large weight of the panels often times requires multiple loads to be delivered to the job site, thereby resulting in potential delays during loading, transportation, and unloading. The large weight also requires the use of an expensive, heavy crane for panel installation.
Insulated concrete wall panels with cavities are also known in the art. These wall panels include inner and outer concrete layers, or wythes, with an internal insulation layer and an air gap provided between the concrete layers, so as to be lighter weight than solid walls of the same thickness. Such hollow insulated wall panels are made by separate castings of the first and second concrete layers, with the first concrete layer being completely cured or hardened before the second concrete layer is poured. This construction method involves long delays and increased costs for the production process.
Furthermore, the prior art concrete wall panels are normally butted side to side with additional panels so as to form a wall structure. However, such a butt joint is not interlocked and thereby complicates the assembly process. In addition, the prior art concrete wall panels are constructed using metallic connectors with high thermal conductivities.
Precast concrete wall panels have recently been introduced which include inner and outer concrete layers, an internal insulation layer, and an air gap between the insulation layer and one of the concrete layers. In constructing the wall panels, the first concrete layer is poured into a form. The insulation layer is supported in a spaced relation above the first concrete layer, and the second concrete layer is poured on top of the insulation layer while the first concrete layer is still wet. Thus, the first and second concrete layers cure substantially simultaneously. A plurality of connectors or rods extend through the foam with opposite ends embedded in the first and second concrete layers. An enlarged flange on each connector supports the insulation layer above the first concrete layer to provide an air gap therebetween.
After the concrete layers have hardened, the wall panels can be lifted and installed in a vertical orientation on footings or another base. The edges of the panels may be contoured, so as to matingly engage with a corresponding edge on an adjacent panel, thereby providing an interlocking joint between adjacent panels. The panels can be assembled adjacent one another and on top of one another so as to provide a form which becomes an integral part of the wall structure. The assembled panels create a continuous form, with the air gap in the panels being filled with concrete. Prior to filling the air gap, the joints between panels may be filled with a sealant or foam, thereby reducing the potential for leakage during filling of the air gap with on-site concrete.
The upper edges of the inner concrete layer may include a notch to receive a floor or roof joist. The joists are thus supported by the inner concrete layer of the wall panels without the need for a ledger beam attached to the inside face of the wall panels. The thickness of the insulation layer can be determined based upon thermal insulation requirements as well as upon mechanical requirements for the insulation material acting as a concrete form. Where required for mechanical purposes, enhanced insulation material may be used incorporating fiber reinforcement, surface laminations, increased density or combinations thereof.
Accordingly, a primary objective of the present invention is the provision of an improved method of forming concrete wall panels.
Another objective of the present invention is the provision of an improved hollow concrete wall panel.
A further objective of the present invention is the provision of a lightweight insulated wall panel useful in forming an integral concrete wall structure.
Yet another object of the present invention is the provision of an insulated wall panel that has an air gap between the outside wythe and the insulation that remains following use of the wall panel in the construction of a concrete wall structure.
A further objective of the present invention is the provision of a hollow concrete wall panel wherein the connectors also provide support for reinforcing grids used for reinforcing the concrete wythes.
Another objective of the present invention is the provision of a quick and easy method of precasting concrete wall panels.
A still further objective of the present invention is the provision of an improved concrete wall panel with a high degree of thermal insulation.
A further objective of the present invention is an improved concrete wall panel which is economical to manufacture and durable and safe in use.
These and other objectives become apparent from the following description of the invention.